Clinical Update: Options in Prenatal and Neonatal Genetic Testing


 
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Laura Fitzgerald, CNM

Obtaining and utilizing genetic information used to be a mystifying future prospect.  However, current clinical practice now demands that all nurses obtain basic genetic competency in order to educate and support patients around the expanding uses of genetic screening. 

Genetic testing staked its firmest claims in obstetrics and pediatrics.  Within these specialties, genetic tests are frequently and routinely ordered.  While medical professionals have developed a comfort level with the influx of additional pre and post-birth information, the general populace faces unprecedented decisions about how much they really want to know.  In the face of occasional fear and confusion about unexpected genetic information, patients often look to nurses to provide consistent guidance.

Most expecting parents experience their first brush with the genetic age early in pregnancy.  One of the tests offered during routine first trimester blood work is the quad screen.  The quad screen measures 4 serum pregnancy markers and is used to assess the risk of Down's syndrome and other neurological disorders in the developing fetus.  It is essential to stress to women and their partners that this test is not definitive. 

The quad screen and other similar genetic tests determine the degree of risk only.  Elevated risk on the quad screen does not indicate the presence of a genetic abnormality but alerts providers to the need for further testing, such as ultrasound screening.  Rates of elevated risk in normal pregnancies are common, causing innumerable false alarms.  Additional testing often produces normal findings. 

Genetic technology can pose difficult questions to prospective parents.  Individuals must be given the opportunity to think about what they would do in the event that multiple tests confirm increased risk.  Patients may be forced to choose, on the basis of non-absolute data, whether or not to terminate pregnancies. 

After a child is born, nurses may find themselves consulted by worried parents who suspect that something is "just not quite right" with their new baby.  Before progressing any further, neonatal and obstetric nurses should complete thorough physical assessments of newborns and obtain full genetic histories from patients.  In many cases parental concerns stem from benign causes such as bruising or edema incurred during labor and delivery.  Trained nurses are able to highlight those clinical findings, such as hypotonia and asymmetry, which may suggest the presence of atypical genetic variation.

If, after a full assessment, the pediatric team concurs that genetic testing is warranted, karyotyping is the most common next step.  A karyotype provides a basic layout of chromosomal information.  It is conducted with 2-5 mL samples of newborns' blood.  From there, extended banding chromosome studies may be ordered to investigate more subtle aspects of genetic variation.  In some cases, even more sophisticated genetic tests are useful.  Florescence in situ hybridization studies, for example, can increase the specificity of diagnoses. 

It can take up to two weeks for the results of genetic tests to return.  In the meantime, nurses are invaluable communication links between the medical team and worried families.  While it is essential that families are paired with skilled genetic counselors who can help patients interpret the meaning of genetic results, nurses are in a unique position to support patients throughout the process.  In short, genetic competency increases nurses' ability to provide high quality, compassionate care. 

Reference:

Thorngate, L., & Rios, C. (2008). Clinical Care at the Genomic Interface: Current Genetic Issues in Neonatal Testing.  Newborn and Infant Nursing Reviews, 8(1), 36-42.

 

Copyright 2008- American Society of Registered Nurses (ASRN.ORG)-All Rights Reserved



 
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